Superoxide produced by Kupffer cells is an essential effector in concanavalin A-induced hepatitis in mice.
Although concanavalin A (Con-A)-induced experimental hepatitis is thought to be induced by activated T cells, natural killer T (NKT) cells, and cytokines, precise mechanisms are still unknown. In the current study, we investigated the roles of Kupffer cells, NKT cells, FasL, tumor necrosis factor (TNF), and superoxide in Con-A hepatitis in C57BL/6 mice. Removal of Kupffer cells using gadolinium chloride (GdCl(3)) from the liver completely inhibited Con-A hepatitis, whereas increased serum TNF and IFN-gamma levels were not inhibited at all. Unexpectedly, anti-FasL antibody pretreatment did not inhibit Con-A hepatitis, whereas it inhibited hepatic injury induced by a synthetic ligand of NKT cells, alpha-galactosylceramide. Furthermore, GdCl(3) pretreatment changed neither the activation-induced down-regulation of NK1.1 antigens as well as T cell receptors of NKT cells nor the increased expression of the CD69 activation antigen of hepatic T cells. CD68(+) Kupffer cells greatly increased in proportion in the early phase after Con-A injection; this increase was abrogated by GdCl(3) pretreatment. Anti-TNF antibody (Ab) pretreatment did not inhibit the increase of Kupffer cells, but it effectively suppressed superoxide/reactive oxygen production from Kupffer cells and the resulting hepatic injury. Conversely, depletion of NKT cells in mice by NK1.1 Ab pretreatment did suppress both the increase of CD68(+) Kupffer cells and Con-A hepatitis. Consistently, the diminution of oxygen radicals produced by Kupffer cells by use of free radical scavengers greatly inhibited Con-A hepatitis without suppressing cytokine production. However, adoptive transfer experiments also indicate that a close interaction/cooperation of Kupffer cells with NKT cells is essential for Con-A hepatitis.


CONCLUSIONS
Superoxide produced by Kupffer cells may be the essential effector in Con-A hepatitis, and TNF and NKT cells support their activation and superoxide production.
Nakashima
Hiroyuki
H
Department of Immunology and Microbiology, National Defense Medical College, Tokorozawa, Saitama, Japan.
Kinoshita
Manabu
M
Nakashima
Masahiro
M
Habu
Yoshiko
Y
Shono
Satoshi
S
Uchida
Takefumi
T
Shinomiya
Nariyoshi
N
Seki
Shuhji
S
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D002450:Cell Communication; D056486:Chemical and Drug Induced Liver Injury / Q000378:metabolism* / Q000473:pathology; D003208:Concanavalin A / Q000009:adverse effects* / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D005682:Gadolinium / Q000494:pharmacology; D007371:Interferon-gamma / Q000378:metabolism; D007694:Killer Cells, Natural / Q000378:metabolism / Q000473:pathology; D007728:Kupffer Cells / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D000097382:CD68 Molecule
D000893:Anti-Inflammatory Agents; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D003208:Concanavalin A; D016207:Cytokines; D005682:Gadolinium; D007371:Interferon-gamma; D017382:Reactive Oxygen Species; D013481:Superoxides; D014409:Tumor Necrosis Factor-alpha; C081026:CD68 protein, mouse; D000097382:CD68 Molecule; C038958:gadolinium chloride